Climate refugees redux: Climate change could tap out Colorado River

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"Lake" Powell, one of the big Colorado River reservoirs threatened by climate change. Photo courtesy University of Colorado.

Climate refugees. There it is again, this notion that large-scale migrations caused by climate change could be in the offing.

When we wrote about this a few months ago based on a climate conference in Seattle, the story got a lot of attention. Today this climate-refugees idea came up again in a story by Bruce Finley of the Denver Post on a new study of climate change’s possible effects on the Colorado River.

The study (sorry — no link; it’s not posted to the Web yet) says there’s up to a 50-50 chance of seeing Colorado River reservoirs run dry by mid-century, given current management practices, increased demand and the expected drying effects of climate change.

Now, that last one’s not something that’s easy to quantify in a projection. But lead author Balaji Rajagopalan of the University of Colorado and other researchers simply took a look at what would happen if water in the Colorado River system were reduced 10 percent or 20 percent due to hotter temperatures (which would increase what the water wonks call evapotranspiration, a combination of evaporation and plants’ transpiring of water.)

Well, guess what? By mid-century there’s about a 50-50 chance of the Colorado River’s two major reservoirs, Lake Powell and Lake Mead, will run dry. That’s under the 20 percent reduction scenario. If the water-reduction comes in at just 10 percent, the chances of reservoirs running dry would be about one in four. We’re talking here about a river that some 30 million people rely on for water (including those in Los Angeles and Phoenix — why nothing in their newspapers on this study?)

Now, here’s the part of Finley’s story that caught our attention. He interviewed David Little, director of planning for Denver Water. Little played down the new study, pointing to other earlier studies that predict the upper Colorado Basin will grow wetter in coming years. Finley reports:

If overuse and climate change did dry up lower basin reservoirs such as Lake Powell and Lake Mead, Denver could see an influx of people, Little said. People in California, Nevada, Arizona and New Mexico ‘are going to tend to migrate to places where they have water.’

Now, bear in mind that the Colorado River basin is already in its 10th year of drought. The side of reservoirs like Lake Mead and Lake Powell show bathtub-like rings far above the current water level, reminding passersby that water remains quite short.

We had to chuckle at the way the Las Vegas Sun cast the story: Colorado River supply safe through 2026. Nothing to see here, folks. Move it along. (To be fair to the Sun, the study says the chances of drying up reservoirs by 2026 is less than 10 percent. And the authors of the study emphasize that, even after that, with proper management, the chances of avoiding reservoir drawdowns can be increased substantially — but not avoided.)

Readers, I’m quite interested to find out about other studies on what climate change might hold for the West — including Mexico and Canada, eh? So if you know of studies like that, will you please let me know? E-mail me at rmcclure (at) invw.org, OK? Remember, InvestigateWest is counting for help on a cadre of ordinary citizens, scientists, journalists, and others who are interested in the issues of environment, public health and social justice in West. Please help us help the West.

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